Rafael Nadal of Spain celebrates with the championship trophy after beating Daniil Medvedev of Russia in the men’s singles final on day fourteen of the 2019 U.S. Open tennis tournament at USTA Billie Jean King National Tennis Center on Sept 8, 2019. Image: Robert Deutsch-USA TODAY Sports

Rafael Nadal won his 19th Grand Slam title after holding off Russian Daniil Medvedev's exhilarating fightback in one of the greatest US Open finals.

Spain's Nadal, 33, won 7-5 6-3 5-7 4-6 6-4 against the fifth seed in New York.

Nadal, seeded second, was cruising at two sets and a break up, only for Medvedev to force a decider.

But Nadal stopped his momentum to clinch a thrilling win in four hours and 50 minutes - just four minutes shorter than the longest US Open final.

Nadal's victory moves him within one of Swiss rival Roger Federer's all-time leading tally of men's Grand Slam victories.

"It has been one of the most emotional nights in my tennis career," Nadal said. "It has been an amazing final. It has been a crazy match."

After taking his third match point, Nadal collapsed to the court in celebration, covering his face as contemplated another famous victory which epitomised all of his fighting spirit.

Medvedev, 23, trudged around the net to warmly congratulate his opponent, who looked on the verge of tears as he hid behind his sweat-soaked vest while taking rapturous acclaim.

"I just want to congratulate Rafa, a 19th Grand Slam title is something unbelievable, outrageous," said Medvedev, who looked mesmerised as he watched a video montage of Nadal's achievements.

Those lucky enough to be watching among a near 24,000 capacity crowd were regularly left open-mouthed at what they witnessed, with the majority jumping to their feet and celebrating wildly after every point, helping create an electric atmosphere on a noisy Arthur Ashe Stadium.

Rafael Nadal of Spain returns a shot against Daniil Medvedev of Russia in the men's singles final on day fourteen of the 2019 US Open tennis tournament at USTA Billie Jean King National Tennis Center on September 8, 2019. Image: Danielle Parhizkaran-USA TODAY Sports

Ultimately it was too late as he was unable to become the first man outside Nadal, Federer and Serbia's world number one Novak Djokovic to claim one of the sport's biggest prizes since Stan Wawrinka's victory here in 2016.

Nadal, Federer and Djokovic have won the past 12 Grand Slams after the Spaniard lifted the trophy in New York for a fourth time.

Now Nadal has the chance to draw level with 38-year-old Federer, who was nine titles better off than his long-time rival in 2007, at the Australian Open in January.

Emotional Nadal outlasts latest young challenger

Despite Nadal, Federer and Djokovic being in their 30s, nobody has been able to break their stranglehold on the men's game and Medvedev was the latest to fall short after a heroic effort.

That has allowed the illustrious trio to pile on the Grand Slam victories over the past three years, livening up the race to be crowned the greatest of all time, which Federer once seemed certain to win.

Nadal, who also won his 12th French Open title earlier this year, is now within one of Federer's tally for the first time.

The magnitude of his achievements - which were shown on the big screen inside Ashe - hit the emotional Spaniard, who broke into tears while he sat in his chair and watched them.

That was a release of all the expendable emotional energy built up over the final two sets of a match which, against a less inspired opponent, he may have wrapped up much earlier.

A couple of hours before, Nadal appeared to be heading to a dominant three-set win against Medvedev, who was the first Russian man to compete in a Grand Slam final since Marat Safin at the 2005 Australian Open.

A physical contest, where both men jousted for supremacy as they tried to outlast each other in brutal rallies, seemed to be going to end in familiar fashion when Nadal broke for a 3-2 lead in the third set.

From somewhere, Medvedev summoned the strength to not only survive but threaten to produce one of the most memorable comebacks ever seen.

But Nadal's intensity allowed him to eventually outlast the wiry Russian who, despite struggling with a quad injury during the tournament, continued to hang in even as the clock approached five hours.

Nadal's mental resilience saw him through in the end, despite Medvedev producing another fightback from a double break down at 5-2 in the decider.

A fourth victory at Flushing Meadows seals another stellar year for Nadal, who reached three Grand Slam finals in the same year for the fourth time of his incredible career.